It may not be an exact fit for your needs, but Legend Keeper (https://www.patreon.com/legendkeeper) may work.
The ultimate writing and organization tool for game masters, writers, and worldbuilders. LegendKeeper is a cloud-based application for building and organizing fictional worlds for authors and RPG enthusiasts. Write articles, upload maps, drop pins, create secrets, and invite your friends to explore it all with a powerful access control system.
I haven't used it but did stumble upon it on Reddit some time ago. It seems to have a great community.